Final answer:
Adjustments in blood delivery are made primarily in the arterioles. They regulate blood flow and pressure by constricting or dilating. During exercise, arterioles in the muscles dilate to increase blood flow.
Step-by-step explanation:
Adjustments in blood delivery are made primarily in the arterioles. Arterioles are small blood vessels that connect the arteries to the capillaries. They play a crucial role in regulating blood flow and blood pressure.
Arterioles have smooth muscle fibers in their walls, which allows them to constrict or dilate in response to changes in the body's needs. This helps to control the distribution of blood to different tissues and organs.
For example, during exercise, arterioles in the muscles dilate to increase blood flow, while arterioles in the digestive system constrict to redirect blood away from nonessential processes.